[.UI/FORM] How to Remove Elements fram the layout?

Hello , me again...
I'm add a QWidget dinamically to my layout. Now I'm trying to remove this same element and I could not do that... I search for code, read the doc and make a test drive desing and still coun't remove this QWidget...

mlong... It's hard to me explain to you what I need... but my application will have a lot of screens and depends on the side menu bar (similar to Qt Creator) the main screen of my app will show the recurses (in Qt Create it's similar to the code editor, Desing, projects screens...)